Generally, container filling operations in automated food processing plants include devices for diverting a continuous stream of containers from a conveyor to an adjacent weighing/filling assembly, which includes mechanisms for weighing each container and adding an approriate amount of filler material to bring the weight of the container to within desired tolerances of a target weight. In most cases, the target weight will be the weight shown on the label of the container. The weighing/filling assembly may be used for filling either completely empty containers or containers that have been partially filled in a prior step in the operation.
The design considerations underlying container filling operations are generally directed to three functions: (1) controlling the movement of each consecutive container as it is diverted from the conveyor to an individual weighing station or platform on the weighing/filling assembly; (2) monitoring the weight of each individual container and calculating the amount of filler material that must be added to the container; and, (3) applying precisely measured portions of filler material to the container to bring the container's weight to within selected tolerances of the target weight. These three functions must be performed at high speeds for optimal productivity, and for extended periods of time with minimum downtime for equipment repair or replacement. Furthermore, for maximum versatility the filling operation should be controllable so that the various operational parameters (target weight, tolerances, etc.) can be readily changed to accommodate various types of filler material and a wide range of container sizes.
The patents issued to Moreno (U.S. Pat. No. 3,556,234) and Pryor et al. (U.S. Pat. No. 4,407,379) disclose filling devices that include a rotating table having a plurality of individual weigh stations or platforms disposed along the perimeter of the table. A series of containers are consecutively transferred from an adjacent linear conveyor onto the weigh stations. Once situated on the weigh stations, the individual containers are filled via overhead spouts or funnels with either liquid (such as oil, as discussed in Moreno) or other free-flowing matter (such as powder, as exemplified in Pryor et al.).
Prior filling devices, directed as they are to dispensing liquid or free-flowing filler material, do not address the special problems that arise when viscid or cohesive matter (such as ground raw fish) is used as filler material. This type of filler material must be forcibly directed into the container in controlled discrete portions. Furthermore, the dispenser used for directing such material must be durable and rapidly responsive to its controls in order to withstand the rigorous service requirements of modern food processing equipment.
Additionally, the container control system, which directs the containers from the conveyor onto the weigh stations, must be capable of receiving the containers from the main conveyor system and swiftly transferring the containers onto and off of the weighing/filling assembly in rapid succession in order to maximize the productivity of the operation.